.What caused the accident and who was responsible for it____a mystery to us.

分类: 作业答案 • 2021-12-28 15:00:18

问题描述：

.What caused the accident and who was responsible for it____a mystery to us.
A.remains B.remain C.is D.look like应选什么?为什莫?

答

B 缺少谓语,主语是复数